books.google.de - In "Marco Polo was in China" Hans Ulrich Vogel offers an innovative look at the highly complex topics of currencies, salt production and taxes, commercial levies and other kinds of revenue as well as the administrative geography of the Mongol Yuan empire. The author s rigorous analysis of Chinese sources...https://books.google.de/books/about/Marco_Polo_Was_in_China.html?hl=de&id=Ydo_9TEmuVQC&utm_source=gb-gplus-shareMarco Polo Was in China